US10800450B2ActiveUtilityA1

Steering assistance system and method

51
Assignee: FORD GLOBAL TECH LLCPriority: Mar 31, 2017Filed: Mar 30, 2018Granted: Oct 13, 2020
Est. expiryMar 31, 2037(~10.7 yrs left)· nominal 20-yr term from priority
B62D 15/0255B60W 2050/0019B62D 6/003B62D 15/0265B60W 50/00B60W 2710/20B62D 5/0463B60W 30/09B62D 15/024
51
PatentIndex Score
0
Cited by
12
References
16
Claims

Abstract

A method for determining a steering angle amplitude of a steering wheel of a vehicle likely to occur during a lane change, including determining a steering angle measured value of a steering wheel of a vehicle at a time of measurement during a lane change; determining a steering angular velocity measured value of the steering wheel at the time of measurement; and determining a steering angle amplitude likely to occur during the lane change at a later point in time than the time of measurement based on the at least the steering angle measured value at the steering angular velocity measured value at the time of measurement.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
       1. A method for determining a steering angle amplitude of a steering wheel of a vehicle likely to occur during a steering maneuver, comprising:
 a steering assist system; 
 providing a steering assist with the steering assist system; 
 at least one sensor, said sensor detecting steering wheel movements applied by a driver of the vehicle to the steering wheel, said at least one sensor generating a steering wheel angle value and steering wheel angular velocity value; 
 measuring the steering wheel angle value at a time of measurement during a steering maneuver; 
 measuring the steering wheel angular velocity value at the time of measurement; 
 determining a steering angle amplitude likely to occur during the steering maneuver at a later point in time than the time of measurement based on the measured steering wheel angle value and the measured steering wheel angular velocity value at the time of measurement; and 
 controlling the steering assist provided by the steering assist system during the steering maneuver based on a deviation of the likely occurring steering angle amplitude value from a threshold value. 
 
     
     
       2. The method of  claim 1  wherein the determination of the likely occurring steering angle amplitude includes weighting at least the measured steering wheel angular velocity value with a normalization factor dependent on an estimated steering frequency value. 
     
     
       3. The method of  claim 2  wherein the estimated steering frequency value is between 0.6 Hz and 0.8 Hz. 
     
     
       4. The method of  claim 2  wherein the estimated steering frequency value is determined as 
       
         
           
             
               
                 
                   f 
                   est 
                 
                 = 
                 
                   min 
                   ⁡ 
                   
                     ( 
                     
                       
                         f 
                         max 
                       
                       , 
                       
                         1 
                         
                           2 
                           ⁢ 
                           
                             ( 
                             
                               
                                 t 
                                 m 
                               
                               - 
                               
                                 t 
                                 0 
                               
                             
                             ) 
                           
                         
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       when t 0 ≤t m ≤t 1 , wherein t m  is the time of measurement, t 0  is the point in time of the beginning of steering to begin the steering maneuver, t 1  is the point in time of the beginning of a counter-steering to terminate the steering maneuver, and f max  is an estimated maximum steering frequency value. 
     
     
       5. The method of  claim 2  wherein the likely occurring steering angle amplitude is determined as 
       
         
           
             
               
                 
                   Δ 
                   est 
                 
                 = 
                 
                   
                     
                       α 
                       stw 
                       2 
                     
                     + 
                     
                       
                         ( 
                         
                           
                             1 
                             
                               2 
                               ⁢ 
                               π 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 f 
                                 est 
                               
                             
                           
                           ⁢ 
                           
                             
                               α 
                               . 
                             
                             stw 
                           
                         
                         ) 
                       
                       2 
                     
                   
                 
               
               , 
             
           
         
       
       wherein α stw  is the measured steering angle value, {dot over (α)} stw  is the measured steering angular velocity value, and f est  is the estimated steering frequency value. 
     
     
       6. The of  claim 2  wherein the likely occurring steering angle amplitude is determined as 
       
         
           
             
               
                 
                   Δ 
                   est 
                 
                 = 
                 
                   max 
                   ⁡ 
                   
                     ( 
                     
                       
                          
                         
                           α 
                           stw 
                         
                          
                       
                       , 
                       
                          
                         
                           
                             1 
                             
                               2 
                               ⁢ 
                               π 
                               ⁢ 
                               
                                   
                               
                               ⁢ 
                               
                                 f 
                                 est 
                               
                             
                           
                           ⁢ 
                           
                             
                               α 
                               . 
                             
                             stw 
                           
                         
                          
                       
                     
                     ) 
                   
                 
               
               , 
             
           
         
       
       wherein α stw  is the measured steering angle value, {dot over (α)} stw  is the measured steering angular velocity value, and f est  is the estimated steering frequency value. 
     
     
       7. The method of  claim 1  including a steering assistance system that generates an additional steering torque during the steering maneuver. 
     
     
       8. The method of  claim 1  wherein the measured steering wheel angle value, the measured steering wheel angular velocity value, and the determination of the steering angle amplitude likely to occur during the steering maneuver at a later point in time than the time of measurement take place at least over a measurement period for multiple times of measurement. 
     
     
       9. The method of  claim 8  wherein the determination of the likely occurring steering angle amplitude includes an averaging of multiple likely occurring steering angle amplitudes determined in the measurement period at different times of measurement
 or includes a low-pass filtering of a steering angle amplitude determined continuously over the measurement period. 
 
     
     
       10. The method of  claim 7  wherein if the likely occurring steering angle amplitude is greater than a stability threshold value assigned to a stable driving state of the vehicle the steering torque additionally generated by the steering assistance system is disengaged. 
     
     
       11. The method of  claim 10  wherein the stability threshold value depends on a speed of the vehicle. 
     
     
       12. The method of  claim 7  including:
 determining a required steering angle amplitude; and 
 comparing the likely occurring steering angle amplitude and the required steering angle amplitude. 
 
     
     
       13. The method of  claim 12  wherein the determination of a required steering angle amplitude takes place according to the speed of the vehicle and a distance between the vehicle and an obstacle. 
     
     
       14. The method of  claim 13 , wherein the determination of a required steering angle amplitude takes place according to the speed of the obstacle, a required lateral offset, or a grip of the road. 
     
     
       15. The method of  claim 12  wherein if the comparison finds the likely occurring steering angle amplitude is greater than the required steering angle amplitude, the steering torque additionally generated by the steering assistance system is reduced. 
     
     
       16. The method of  claim 12  including a comparison of the likely occurring steering angle amplitude with an upper threshold value; when the comparison finds the likely occurring steering angle amplitude is greater than the required steering angle amplitude and is greater than the upper threshold value the steering torque additionally generated by the steering assistance system is disengaged.

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